Probing Parenago: A Dialogue on Stellar Discontinuity

byPaul GilsteronApril 26, 2019

The publication of a paper called “New Features of Parenago’s Discontinuity from Gaia DR1 Data” by V. V. Vityazev and colleagues brought us a new look at an unusual observation. Parenago’s Discontinuity refers to the fact that red, cooler stars move faster in the direction of galactic rotation than blue, hotter stars, based on Hipparcos data. But is the phenomenon just a chance, local observation? Fortunately, a much larger dataset from the Gaia mission has now become available, and it is this that the Vityazev paper addresses in terms of Parenago’s finding. The following dialogue between Greg Matloff and Alex Tolley goes to work on the Vityazev document. Dr. Matloff has pointed to the Discontinuity as a possible marker of consciousness among low temperature stars, where molecular bonds can form.

Could motion be a matter of agency in such stars? Greg explored the idea in his book StarLight, StarBright. Now Alex digs into the Vityazev paper and questions whether Greg is right that his controversial theory can be falsified given our data. Various mechanisms for stellar motion are explored, ranging from coronal mass ejections to possibilities that are downright Stapledonian. How exactly would a civilization go about moving stars? I am preserving the dialogue format of the original correspondence as a case in point of serious differences being discussed in a way that both disputants have found valuable.

By Greg Matloff and Alex Tolley

Alex: Greg, in your 2012 Centauri Dreams post Star Consciousness: An Alternative to Dark Matter, you made the claim that there was an alternative explanation to dark matter for the velocity of stars around the galactic center. Your hypothesis was some sort of psychokinesis effect generated by consciousness, even if a primitive one. You used the Parenago Discontinuity (PD), which showed that velocity was related to star type, to suggest that fast stars were cool and that these cool stars could have chemistry, allowing some sort of consciousness. The 2015 Centauri Dreams post Greg Matloff: Conscious Stars Revisited further elaborated on this hypothesis.

The first problem I have with the data you used is that there was no plateau of velocity, but rather a peak, unlike the classic Parenago Discontinuity, which showed a plateau. This would imply that star types reach a peak velocity, then decline. Why would there be such an effect if consciousness was the driver of some psychokinetic effect? A possible explanation could be the amount of material that could be expelled to propel the stars.

The issue was left on whether the Parenago Discontinuity was purely a local, rather than galactic effect. We awaited the Gaia data.

The Vityazev paper using Gaia data confirmed that the Parenago Discontinuity was indeed non-local and that the peak effect around B-V of 0.7 seen with the earlier data you presented was indeed correct. As you had hung the hypothesis on the Parenago Discontinuity, this confirmation with the larger data did not falsify the interpretation that stars might be conscious.

The Hipparcos satellite measured the distances to hundreds of thousands of stars. It also measured the magnitude of each star through two filters:

A blue filter, yielding a B (for “blue”) magnitude

A greenish filter, yielding a V (for “visual”) magnitude (the human eye has highest sensitivity in the green)

Now, astronomers call the difference between the B and V magnitude of a star its (B-V) color, or sometimes just “color” for short. Remember how magnitudes work: large numbers mean “faint”, and small numbers mean “bright”. What is the “(B-V) color” of a hot star?

Figure 5 in the Vityazev paper seems to offer the basis for the more likely explanation of the PD results.

The figure 1b graph (left) shows the PD with the Gaia data. The figure 5 chart (right) shows that the PD effect is correlated with stellar age, rather than stellar temperature. The cooler stars in the sample are actually younger than G stars at the age peak. The shape of the B-V vs age graph matches the B-V vs azimuthal velocity (V) graph. This seems to me to suggest that velocity is therefore related to age, and more likely due to some physical factor related to time.

This seems to me to be the most parsimonious relationship and should be chosen by Occam’s razor. The stellar conscious hypothesis has to account for this age relationship and explain why the coolest stars that should have good consciousness and can, for unknown reasons and unknown mechanisms, chase around the galaxy faster than large, hotter stars, nevertheless go more slowly than G-type stars.

Why stars increase velocity with age still needs elucidation and modeling. However, the Vityazev paper has broken down the many components of stellar kinematics. This should provide a nice set of constraints for validating computational models.

Greg: The fact that Parengo’s Discontinuity is apparently non-local supports my hypothesis and does not support density waves. I have gone through the Messier, Herschel, and NGC Catalogues and reported my results in several publications. No known diffuse nebula in our galaxy or the Clouds of Magellan is large enough to drag along stars over a ~1,000 light-year radius sphere. The fact that stars seem to move faster along the direction of galactic motion as they age is very interesting, but it does not bear upon my original hypothesis that the discontinuity occurs at the point where molecules come in to stellar spectra. It is in my data as well as the data in the paper, so I presume that it is correct. I had originally ignored it because it does not bear on the original hypothesis. I presented in my original letter to Paul and others the causes I could think of to explain this phenomenon. But please, don’t hesitate to present others.

I am pretty happy right now because I predicted a non-local Parenago Discontinuity and this has apparently been verified. No one else, to my knowledge, had made this prediction. The local alternative explanations are now extinct. But science works by constructing alternative explanations for a phenomenon and testing them. Please do so. Try your hand at galaxy-wide possible alternative explanations. I can think of a few that won’t work. I am very interested in what you and others come up with and look forward to a dialogue of competing ideas.

Alex: The chart below is a rough conversion of the B-V values to age (from Figure 5) and the velocity from figure 1b. This seems to show that the Parenago Discontinuity might be a phenomenon based on using a variable (stellar type) that isn’t really related to the star’s velocity. Using age provides an approximately linear trendline with an R-squared of 0.93.

I accept that this velocity might be hard to explain (I am certainly not able to comment on this) but the relationship of age to velocity does seem to point to a simpler explanation for V based on natural forces, rather than requiring agency.

This older reference looked at A and B stars and examined the velocity differences based on age. There were clear differences based on age, rather than stellar type. While this doesn’t invalidate your hypothesis, they do have a physical explanation on why age impacts star velocity. To my mind, such approaches should be examined further before resorting to more exotic explanations. With the Gaia data, astronomers involved in kinematics studies now have a trove of high-quality data to test their models. I would be looking amongst that cadre for cutting-edge modeling.

Greg: Nice analysis! What I tried to do is put all the cards, as I see them, on the table. I am not and never have been an advocate for psychokinesis. But science seems willing to accept the Multiverse, which can perhaps not be verified. It accepts dark matter and invokes many properties for this stuff even though it remains hidden. I have discussed PK and the Geller/Randi controversy with people on both sides and find nothing wrong with their arguments. So I believe, with David Kaiser of MIT and others, that the case should be reopened. If a weak PK force can be demonstrated to the satisfaction of the scientific community, it should be considered an option.

I also believe that the stellar age variation has little to do with Parenago’s Discontinuity. Why does the discontinuity appear at the same place where molecules come in to stellar spectra?? And why indeed is it a discontinuity instead of a smooth curve? Invoking strange (and unknown) stellar variability to explain it is certainly an exotic explanation!

One of the problems with what we are discussing comes from the fact that I was checking the metaphysics of Olaf Stapledon, a sci-fi author and philosopher, and attempting to see if there is something scientific behind his discussion in Star Maker. If I were starting afresh, I would title my work (as I have done in subsequent papers) “A Test of Self-Organization on the Galactic Scale?”, since astrophysicist Erich Jantsch uses “self-organization” as a possible explanation of consciousness. Alternatively, I might go with the terminology of philosophers such as David Chalmer and title my papers “Is Panpsychism a Science?”

I think that the work that you have done on (B-V) vs. star age from the Gaia Release 1 sample is invaluable and should be included in our published dialogue. I hope very much that our debate leads to further work with future Gaia data releases.

Alex: Let me give you a perspective from a biologist’s point of view. The Parenago Discontinuity might have an analogy to living vs non-living, where living things can be observed to grow, move (or have tropisms), reproduce, etc. Let us assume that cooler stars have some sort of motility which is driven by a “need”, perhaps acting something like a bacterium. Bacteria can be observed to move faster in their medium if they have flagella. A biologist would ask “what is the evolutionary advantage of movement given the cost” and might hypothesize that this leads to faster food discovery, or a phototropism, or evasion of larger predators. In the case of cool stars, I would be asking similar questions. Why is V (azimuthal velocity) the key variable, rather than a different direction (U, W)?

Given that V is affected by star type, what is the advantage of moving faster in one direction? One might hypothesize that this facilitates sweeping up of neutral gas clouds more effectively, but this would be even better if the stars moved in the opposite direction. Are the stars perhaps self-organizing into “flocks” and what we are seeing is the movement of the flock which is currently going in the V direction? With bacteria, we know that it is flagella that allow movement through the medium. With stars, one mechanism is with a Shkadov drive to asymmetrically create thrust. Another might be directed coronal mass ejections (CMEs). In the former case, it is not the star that is sentient, but more likely a separate intelligence, a more Stapledonian idea.

Therefore another hypothesis is that stars are being driven by a galactic wide intelligence[s] to reach a certain unified velocity for some reason. The age relation to velocity then makes sense if the Shkadov drives need billions of years to reach the needed velocity. For what purpose?

One idea might be to facilitate more frequent stellar encounters allowing biological civilizations to disperse more easily among the stars. On the other hand, if the galaxy is an organism or superorganism, perhaps the Parenago Discontinuity is some process to organize older stars for some equivalent of a cellular process.

An obvious question suggests itself. If cooler stars are somehow able to direct their velocity, shouldn’t very cool stars, i.e. red dwarfs and brown dwarfs, also have that behavior? We don’t have enough examples of BDs to determine this, but it would provide another datum. One might extend this to gas giant planets too. While the ones we know about are bound to their stars, is it possible that planetary migration is a related phenomenon? Are “hot Jupiters” exhibiting similar behaviors?

Clearly one can speculate endlessly. If the relevant variable is time rather than stellar type, then this constrains mechanisms to those that require both time and a reason for the more uniform direction. With such a constraint, looking for a natural process that requires billions of years would seem to be the most fruitful direction. That velocity W (fig 1c) is fairly constant, but U (fig 1a) declines with stellar type suggests to me that physical forces are somehow directing the movement into the W direction, whether those forces are natural or artificial. The direction is apparently translating from U, towards the galactic center, to V, a transverse direction, rather like the Coriolis forces operating on weather patterns that “shape” the velocity profile.

If time is the relevant variable, then looking for young, cool stars should be the best way to test the hypothesis. If they are fast, then stellar type is the key variable, but if slow, then time. The Vityazev paper also has limited data for red giant stars. If anything, the G, K and M red giant stars have more uniform V than main sequence stars, i.e. they seem to conform more closely to the classic PD plateau. Whatever the mechanism, size is clearly not a variable as they have velocities comparable to the oldest G stars. Creating an age chart for these stars might also be instructive.

Unfortunately, even if age is the relevant variable, it doesn’t falsify your hypothesis. The mechanism of acquiring a high V might simply require time, whether a natural, external force or an inner, self-directed one. Just as with determining which animals are conscious (e.g. using the mirror test), we need a better test to be able to falsify your hypothesis. We may be in the position of trying to determine sentience of a herd of buffalo from a still photograph when what we need is video or many photographs over time.

PS: A back-of-the-envelope calculation shows that a star could attain the necessary velocity by directing its radiant energy (e.g. Shkadov drive), but not by directed coronal mass ejections. (calculation for our sun).

Greg: Wonderful! My feeling has always been that stars need not have a high level of consciousness–they could be like slime-mold amoeba or developing cells in embryos.

I suspect that Vityazev et al could not use the red giant Gaia data for the same reasons the Burnham’s validation of Parenago for giants looks so fluffy. Since most of these stars are very distant, astrometric parallax is impossible with Hipparchus and the early Gaia data.

Spectroscopic distance estimates using the HR diagram are accurate to 10% or less. Also, what is the local reference standard when the subject stars occupy a sphere thousands of parsecs in radius? Hopefully, future Gaia data releases will offer the possibility of greater accuracy.

Also, I have been thinking about your suggestion regarding unknown forms of stellar variability. My suggestions in the earlier emails–EM radiation anisotropy and unidirectional jets in mature stars–are two of these. Perhaps there are others!

Greg: The Shkadov thruster could of course be a form of anisotropic EM emission from the star. But could such a thruster develop in a purely materialistic setting not requiring a Kardashev Type 2 civilization in that star’s system or volition on the part of the star?

It is so strange that we are encountering so many fascinating intellectual insights at the same time that national governments are failing. Last Sunday we attended a talk by Tyler Volk, a biologist at NYU. He has constructed a geometric/architectural model of self-organization from the quark to universal levels. Tyler suspects that we are moving towards the planetary phase of our civilization and this is the use of apparent political dysfunction. I hope he is correct.

Alex: Greg, you write: “The Shkadov thruster could of course be a form of anisotropic EM emission from the star. But could such a thruster develop in a purely materialistic setting not requiring a Kardashev Type 2 civilization in that star’s system or volition on the part of the star?”

I would be skeptical about EM emission asymmetry as I would have thought this would be detectable. A Shkadov drive with mirrors would definitely have some observable effects. Even just some “magical” control over EM emissions should be detectable.

While CMEs are not energetic enough, a small star with large CMEs that are accelerated to c might just work. But again, I would think such a beam would be detectable. I agree with you that such EM or particle control would need K2 civilizations to manage. With so many stars that would be exhibiting such high V’s, just by chance we would detect some anomalies, and solve the SETI question too.

It also occurs to me that since our galaxy has experienced a collision with another galaxy or satellite in the remote past, with a corkscrew effect on velocities, is there any chance this might in some way be responsible for the Parenago Discontinuity?

Let me refer to a post here on Centauri Dreams titled Gaia Data Hint at Galactic Encounter. I could imagine that an old collision with another galaxy or similar massive object accelerated stars which retained their higher velocities while younger stars maintain the velocities of birth in a more stable galaxy post-collision. To get the age-related relationship, it suggests that the collision must have had its impact on velocity over billions of years. Perhaps the values of U, W and V can be used to determine the likely form of the collision?

Greg: Regarding the Shkadov thruster discussion, have you read the Benford/Niven novels Bowl of Heaven and Shipstar? These discuss an advanced version of this concept. I have given some thought to a galactic collision producing Parenago’s Discontinuity. According to the computer simulations done at Cornell (and likely other places), when the Milky Way collides with Andromeda to form Milkimedia (what a horrible name!), there will be widespread disruption of diffuse nebulae. This might result in a Spiral Arms Density Wave effect drawing lower-mass stars along faster than their more massive colleagues.

But the same simulations indicate that the combined galaxies lose their spiral shapes after merger. The ultimate result is a giant elliptical with few nebulae and a very low rate of star formation. Since this has clearly not occurred for the Milky Way galaxy (which is a nice barred spiral), it is reasonable to conclude that such a galactic merger did not happen. From what I understand, galactic cannibalism (where a big galaxy gobbles a smaller one) has less disruptive effects–the big guy retains its shape (which might be an argument for self-organization on the galactic scale.

Alex: From an engineering point of view, I think controlling the solar wind might be a lot easier than deflecting the EM with a solid mirror. I would envisage surrounding the star in a charged, superconducting “mesh” to trap the protons. These would be funneled to electromagnetic accelerators to emit the protons in a unified direction at near c velocity. That might be enough to accelerate the star over the needed timescales. The advantage is lower mass requirements and no impact on the star’s light emissions or spectrum. However, I would expect that the proton beam emitted would be detectable. Think of this drive as a giant ion engine coupled with a ramscoop that captures the protons from the star, rather than from the interstellar medium as in a Bussard ramjet.

The Centauri Dreams link I provided was for a proposed “impact” with a dwarf galaxy (the Sagittarius dwarf galaxy). Much smaller than M-31, and if there was an impact, it certainly hasn’t disrupted the shape of our galaxy. What is interesting is the analysis technique that teased out the spiral shape of the velocity-position phase space that was too subtle to visualize with pre-Gaia data. This sort of analysis might offer a better way to understand the stellar type/age vs velocity relationship. Figure 2 in the paper referenced in the article shows the structure in the azimuthal (V) direction vs the radius (I cannot interpret if this has any possible bearing at all on the Parenago Discontinuity, but the same analysis teasing out stellar type might well do. It might be worth contacting the principal author regarding this approach. Paper attached)

Greg: Nice paper! Thanks for it. But can this effect bear on an apparent near-linear relationship between galactic revolution velocity and star age? I think that such dwarf galaxy absorptions by the Milky Way are rare events. Regarding the Shakdov thruster, you are (I think) correct. But could we detect a proton flow necessary to increase V by ~1 km/s over a 10 billion year time interval? Certainly fuel for thought.

Alex: Given the large numbers of stars in the sample, I was thinking that the stellar type vs velocity relationships could be plotted for locations on the galactic disc. If they are all the same, that would tell a different story than if they differed in shape. There is a hint of this in the Vityazev paper where they plot thin vs thick disk stars that show differences. In other words, given the large sample size, it should be possible to show more granularity based on location than with the averaging that Vityazev computes.

Incidentally, I came to the same conclusion with regards to CMEs. However, even for our sun, the CMEs are within a single order of magnitude if they are accelerated to c. As the solar wind produces more protons overall than CME, the same approach might work. However, this approach has to work for all stars, so the mass loss of protons/star mass has to increase for cooler stars for this mechanism to describe the PD observation.

I am not aware of the idea of moving stars by trapping and accelerating the solar wind and flares, so possibly it is novel. I also wonder if it is possible to direct solar flares by manipulating the surface magnetic fields of the star so that they break and cause a flare in desired positions. As the star rotates, the magnetic field is broken when the alignment is correct, releasing the flare. The flare material still needs to be accelerated to have the desired thrust, so electric fields could do that, or something more like a linear particle accelerator. Definitely K2 or even K3 level engineering…or just maybe some phenomenon than a “living” star could manage.

Greg: The differences between disc star velocities and others in the Antoja et al paper is fascinating. I don’t think it bears on Parenago unless somehow large diffuse nebula were created in the galactic merger. These could have perhaps caused differential velocities between massive and less massive stars. But such nebula would have to be perhaps an order of magnitude larger in radius than those in today’s galaxy to encompass a stellar sphere with a radius in excess of 1,000 light years. A further problem is that these structures would have to dissipate in less than 1 billion years, leaving no trace.

But your suggestion of using future Gaia data releases to dig deeper in stellar kinematics is excellent. I hope that someone will check if Parenago’s Discontinuity works for a star sample at a distance, say, of 10,000 light years.

I have done some rough calculations to see if a directional stellar wind or directional coronal mass ejections (CMEs) could accelerate a Sun-mass star by about 1,000 m/s in 1 billion years. Both seem to fail by a few orders of magnitude. But it is most intriguing that stellar flares (and presumably CMEs) are more common in less massive red dwarfs than in Sunlike stars.

Alex: BoE calculation for thrust of solar wind:

For our sun, redirecting the solar wind to a single direction would only result in the sun traveling ~3 m/s after 1 billion years. However, if the particles were accelerated by 3 orders of magnitude to c, that increases the velocity to 3 km/s. Over 5 billion years, that gets you to 15 km/s, which is in the range of the V needed for the Parenago Discontinuity graph. So physically possible. My first thought is that this would be an engineering solution, rather than a natural one – that is K2 – K3 civilizations. The bias in my thinking is that only human engineering can create craft that can travel at supersonic and hypersonic speeds. Birds cannot even manage 0.1 km/s, while our engineering can propel craft in air 1-2 orders of magnitude faster.

I do have a question about the relative emissions of EM and particles from different stellar types. Isn’t the mass loss vs initial star mass going to be the basically the same for all stellar types? If so, wouldn’t all stellar types reach the same velocity by the time they reach the end of their main sequence period? The Parenago Discontinuity relationship suggests mass or age is important, which implies that the acceleration must be approximately constant for all stars. This would imply, naively perhaps, a force more like gravity, that is exerted over the age of the star. It cannot be a point source outside the galaxy; otherwise the rotation of the galaxy would keep changing the direction of the force. Could it possibly be invoked by the [dark] matter in or surrounding the galaxy? Can this force be computed to suggest a possible cause?

Greg: Very interesting speculation. It’s so funny–we needed Gaia to get beyond a few hundred light years. And this early paper of Gaia results (and I am sure many others) will inspire people to generate designs for even more capable space observatories. It seems that every question we investigate and answer results in hundreds of new questions.

I would hesitate to invoke dark matter. It seems to be a catch-all for everything not understood in the universe. I will check out mass loss rates for distant star types. But I don’t know if we have reliable data.

Alex: What is relevant is whether the acceleration is related to stellar type or not. A large, hot star may lose a lot of mass, but it has to accelerate a more massive object. If a star loses X% of its mass over its lifetime, and if the wind speed is fairly uniform across such stars then the final velocity should be much the same for all star types over their lifetimes. The PD requires that this is not the case.

Greg: I just did a Google for “Mass Loss from Main Sequence Stars”. Apparently, this quantity directly depends upon star surface temperature.

I think our dialog has been very fruitful. When I submitted my first paper on the subject to the Journal of the British Interplanetary Society, I had to contend with 4 reviewers. Some of these favored the concept of stellar volition but argued about the inclusion of psychokinetics as a possible explanation. I am neutral regarding this topic, as I have discussed but I am still impressed by the vehemence of the arguments pro and con decades after the Geller/Randi affair. So the fact that accelerated CMEs can provide acceleration of G-type stars (as I agree after a few calculations) indicates that there is an alternative option. I will at some point write up my work on accelerated CMEs and send you the results.

Late this afternoon, weather permitting, we will journey to the Hayden Planetarium, which is hosting a Dutch astronomer who will talk about the latest Gaia results on galactic stellar kinematics. I suspect that Parenago’s Discontinuity is not on the agenda, but I will let you know.

Alex: I note that the Gaia data include all the information needed to create samples of stars within a radius of a position. This could be used to explore the type/mass vs V graphs at the higher granularity that I suggested, particularly radius from the galactic center. This would help confirm that the Parenago Discontinuity is truly global within the dataset and not some averaging, or whether there is spatial structure to the distributions. It may take some computational effort, but it might shed light on possible natural explanations of the PD observation. Sample sets would be easy to crunch on a PC, and the results compiled as a map. For example, the slope of V vs type or mass as a color-coded map.

I was also thinking about the gravity solution. It may work if a point object makes continual passes in the galactic plane. Older stars would experience more passes and if V is due to gravity dragging the stars along during a pass, then this would account for their higher V. A prediction would be that the slope of V would depend on how far from the source the stars are. Dare I say a denser clump of dark matter in a highly elliptical orbit about the galactic center? Data and some modeling would be needed to test this idea.

Out of this discussion, Greg Matloff incorporated many of Alex Tolley’s contributions and produced the short essay below looking at how stars could be accelerated to account for the Parenago Discontinuity.

Physical Methods of Effecting Main Sequence Star Acceleration

Greg Matloff, Nov. 16 2018

Using the Gaia DR1 dataset, Vityazev et al. have investigated Parenago’s Discontinuity for a sample of 1,260,071 main sequence stars [1]. The minimum mean distance for O-k stars in this data release is estimated as 0.15 kiloparsecs, which indicates that the diameter of the sphere containing the subject stars equals or exceeds 1,000 light years. Local explanations for Parenago’s Discontinuity clearly fail.

The analysis reveals that Parenago’s Discontinuity is real. Stars redder than (B-V) about equal to 0.6, which corresponds to spectral class F9 or G0 move faster in their orbits around the center of the Milky Way galaxy than hotter, more massive, bluer stars. Their results are in substantial agreement with the results from Allen’s Astrophysical Quantities and Hipparcos data for a much smaller stellar sample (with a diameter of about 500 light years) presented by Matloff [2].

But Vityazev et al. discuss for the first time a feature present in both data sets. Main Sequence stars apparently speed up in their galactic trajectory as they age. This velocity increment amounts to an increase of about 2 km/s in 8 billion years. The acceleration is approximately equal to 8 X 10-15 m/s2. For a solar-mass star (2 X 1030 kg), the average force exerted on or by the star during the 8 billion year time interval is 1.6 X 1016 N.

Reference 2 presents a number of possible causes for the discontinuity in galactic stellar orbital velocity around (B-V) = 0.6. The analysis presented here considers possible mechanisms that a star might employ to maintain a constant acceleration over a multi-billion year time interval.

1. Acceleration by Nonisotropic Stellar Electromagnetic Emissions

Consider here the possibility that a minded star can control the direction of its electromagnetic emissions. The solar luminosity (Lsun) is 3.9 X 1026 W [3]. Modifying Eq. ((7.2) of Ref. 4, the maximum stellar-radiation pressure acceleration for a Sun-mass star (Msun) is Lsun/ (Msun c) for a unidirectional stellar wind, where c is the speed of light in vacuum (3 X 108 m/s). Substituting in this equation, the maximum solar acceleration from this process is about 7 X 10-13 m/s2.

This acceleration is about 100 times the required stellar acceleration to effect the 1 km/s during a 1-billion year time interval. But if the Sun accelerates using this process, the Solar Constant might vary on an annual basis by up to 1%. Solar Luminosity has been measured to vary by a much smaller amount during the Sun’s 11-year activity cycle.

But the Sun and other main sequence stars generate neutrinos as well as photons as they convert hydrogen into helium deep in the solar (stellar) interiors [3]. Neutrinos have linear momentum as well as very small mass. The solar momentum flux is hard to study because of the very low cross-section of neutrino interactions with detectors. Perhaps stellar neutrino fluxes are not isotropic.

2. Acceleration by Nonisotropic Solar Wind

From Ref. 3, p. 427, the average solar wind velocity is 500 km/s (5 X 105 m/s) and the solar wind carries about 2 million tons of solar matter per second (2 X 109 kg). If all of this material were concentrated in a unidirectional jet, the force exerted on the Sun or Sunlike star is 1015 Newtons. This force is 1/16 the force required for stellar acceleration. This proposed method of stellar acceleration therefore fails.

3. Acceleration by Coronal Mass Ejections

Coronal mass ejections (CMEs) are generally associated with solar flares. Their frequency varies with the solar activity cycle. On average, the mass ejected by CMEs in a Sunlike star amounts to a few percent of the mass ejected in the solar wind and the velocity of a typical CME varies from a few hundred km/s to a few thousand km/s [5]. Unidirectional flares therefore fail as a stellar accelerating mechanism.

4. Acceleration by an Accelerated Solar Wind

Consider next the possibility that a minded Sunlike star can apply its magnetic field to accelerate a unidirectional solar wind to 0.1c (3 X 107 m/s). For the solar wind mass listed above, the kinetic energy of the jet is approximately 1024 W, which is less than 1% of the solar constant. If all of the solar wind is in the jet, the approximate force on the star is 6 X 1016 N. This is about 4X greater than the average force required to accelerate the star.

5. Might the Gravitational Constant of Galactic Mass Vary With time?

Elementary physics students learn that the velocity of an object orbiting a central body varies directly with the square root of the product of the central body’s mass and the Universal Gravitational Constant G. It might be argued that increases in galactic mass or G over billion-year time scales might account for the higher galactic-orbital velocities of older stars.

Surprisingly, as reviewed in an on-line essay by Rupert Sheldrake, experimental measurements of G show some variation [6]. But according to Lorenzo Iorio, such variations are likely caused by experimental errors because the orbits of solar system planets seem relatively constant [7].

A recently published study based upon the Gaia data set demonstrates that within the last 900 million years, at least one dwarf galaxy has passed through and possibly merged with the Milky Way [8]. So it is safe to conclude that the mass of our galaxy may not be constant over multi-billion-year time scales.

But it seems unlikely that either of these two variations can account for the reported increase in stellar galaxy-orbiting velocity with star age. After all, stellar birth nebulae orbit the Milky Way galaxy’s center as do the stars. Infant stars will therefore be accelerated in the same fashion as mature stars by such variations.

6. Conclusions

We see that several of the above suggestions succeed as possible methods of main sequence star acceleration. Perhaps the most intriguing, and the one that might inspire future research, is the possibility that stellar neutrino emissions need not be isotropic.

Psychokinetic (PK) effects have not been considered in the above treatment. Although it is unwise to eliminate PK from consideration for this application and others, it is wise to keep a distance until/unless it can be demonstrated in the laboratory in experiments that can be replicated by other researchers, including skeptics.

Acknowledgement

I greatly appreciate communications and interactions with Alex Tolley. His spirited comments and criticisms were instrumental in preparation of the above discussion.

Would in not be so much simpler, from an Occam’s Razor standpoint, to assert that there is some unknown effect or force that slowly accelerates stars? And since my purported acceleration is slow its effect will require time. Hence older lower mass stars will be accelerated over time more than the higher mass shorter lived stars.

There is so much in Astronomy and Astrophysics that are not understood. The Dark Matter problem being the foremost. Apparently we either do not understand gravity or we don’t understand particle physics. Or are Galaxies sentient beings using PK or magic to achieve their high rotation rates?

Because we don’t know what is the reason for these stars’ motions why leap to a completely unsupported conclusion? If low mass stars are living, sentient beings than what is the evidence for this? What are the “biological” processes that produces life and consciousness in stars?
Can we communicate with these living stars? How do they control their PK? If evidence for these particular questions can’t be shown than we are simply facing another Astronomical unknown.

If you read my earlier contributions to the Blog on this subject, you will follow the logic of my trust of Stapledon’s volitional stars hypothesis. Yes, we know very little and new data is always pouring in. One person who is actively pursuing means of communicating with sentient stars is the British biologist Rupert Sheldrake.

Do you have links to any of Sheldrake’s papers on this subject of communicating with stars? So far what I have been reading about him has not been encouraging. He appears to be making himself a maverick against the science establishment largely for the sake of doing so.

Anyone who thinks science has or knows all the answers is deluding themselves. No self-respecting person would honestly think or say such a thing. It just happens to be the best way we know of to go about investigating reality for now, when done correctly.

Real science is open to plausible concepts, but they need to do more than just have some interesting anecdotes or demand respect because they say so, or that their acolytes think they are the next Galileo being persecuted by the Establishment.

There is a lot of bias among adherents of the dominant scientific views. And there is a lot of stifling of alternative views too. It slows progress. The main science funding models often limit imagination. I’m glad Dr. Matloff and Dr. Sheldrake have the courage to speak their views in a very hostile intellectual environment.

I was referring to Dr. Sheldrake. I am not trying to be hostile, in case any of your words were aimed at me. But I do ask for evidence, which is what science requires. As Carl Sagan once said: “Extraordinary claims require extraordinary evidence.” This is SOP whether it is science or a legal court.

And I would really like to look at Dr. Sheldrake’s paper on his communication with stars.

Sorry, my comment was aimed not specifically aimed at you but just in general. I was just making the point that in my view, the mainstream scientific community sometimes suppresses new ideas by ridiculing them and marginalizing people’s work as opposed to honest published scientific criticism.

BTW, I never liked that quote from Carl Sagan. The same caliber of evidence is required regardless of what the claim is. But that quote is often used as a hammer to basically tell people with new ideas that they’ll never meet the standard to be convincing enough. What critics really mean is that only the right scientists can make radical new claims and be believed. Sheldrake, for example, could actually have the best evidence but it wouldn’t matter because his paradigm is unpopular to the current scientific establishment.

No fan of the self-aggrandizing Sagan (though Contact was great), but his statement stands the test of time and serves as an excellent buffer to pseudo-scientific nonsense woo. BTW, This whole discussion wrapped in the cloak of science kind of has me spooked as a scientist. My initial comments on this blog were reserved, but I know of no serious academic who would entertain these bizarre ideas outside of their own mind. We all have fantastical ideas running through our brains from time to time, but most of us keep them contained until we have real evidence.

Evidence stands on it’s own and doesn’t have to be more or greater simply because the subject is new or controversial. Sagan’s statement is the epitome of scientific bias and should be rejected. It’s like saying some votes count more than others. It allows incredulity and disinterest to be substituted for real science. That statement is untrue and has done a lot of damage.

I can’t tell you how many times when I explain there is now a lot of data showing that hydrogen atoms can exist in a state more tightly bound state that the previously accepted ground state people throw that quote in my face. No amount of careful and precise data is enough because it disturbs their paradigm and doesn’t come from the ‘right’ people. They won’t begin to believe it until sources they trust tell them so. And no one they trust wants to do the work because they predetermined it can’t possibly be correct. The damage is that such a discovery is left floundering in the dark for decades when it could become mainstream knowledge and have technological implications too.

I do not wish to be disrespectful in any way towards the profound ideas presented here. It reminds me of the discovery of pulsars and the initial thought that they may be beacons from an alien intelligence, or the WOW signal, or Tabby’s Star and its improbable mega-structure. Thoughtful speculation sometimes leads us to great discovery, but sometimes it leads us where we want to be lead.

Agreed. I met with Jason Wright at the recent Breakthrough Discuss event in Berkley. The best guess so far for Tabby’s Star is small dust particles. But the people studying this wonderful object realize that they must find a dust source near the star that has operated for at least a century.

Yes, but where is all the dust coming from? Astronomers have postulated such things as two giant exoplanets with huge ring systems and massive swarms of comets. That these relatively easy answers have not caused the “problem” called Tabby’s Star shows that if nothing else, we still have a lot to learn about our Universe.

I too am not a fan of the Milky Way galaxy being a K3 structure. If there is so much intelligence, why has humanity been left out?? But Alex’s supposition is very nice and original. If further data supports the concept of stellar acceleration, it cannot be ruled out.

Would humanity actually recognize if we were embedded in a galaxy that was Kardashev Type 3 civilization? We think we know what such a setup would look and act like, but I have my strong doubts. Plus we have an entire establishment and culture that not only has little to no clue on such matters due to its relative youth and parochialism, most would not accept it even if such evidence were staring them in the face.

Tabby’s Star and Oumuamua are two examples of this, and no I am not saying they are or even have to be of ETI origin. The mere concept alone has stirred up all kind of reactions. Well, we have to start somewhere, don’t we?

That is what Avi Loeb is trying to do, although of course the media and even professionals confuse his actions and comments with an actual declaration of our first interstellar interloper being an alien vessel, when he is “merely” asking them to seriously think outside the box for once, not just pay lip service to the concept. We are going to look incredibly backwards to our descendants some day otherwise.

Thinking outside the box, being able to drop a conceptual framework when the empirical results simply will not fit, is what makes science science. What if memory, or even consciousness, are not emergent properties of biological structures but rather are an intrinsic property of the relationship linking time, space and matter? If true it would go a long way toward explaining the paradox of the double-slit experiment.

I am going to say no because their biological evolution did not require such knowledge. Even if they were deep inside one of those buildings, the ants main concern would be food and how to get it back to the colony.

Speaking of `Oumuamua: Here’s the latest: As you remember, NASA physicist Zdenek Sekania put forward a natural solar radiation pressure alternative to Bialy and Loeb’s “thin film or lightsail” hypothesis. Now he expands on this, strongly challenging ANY hypotheses derived from an added acceleration as a result of outgassing. “Outgassing as a Trigger if 1I `Oumuamua.s Nongravitational Acceleration: Could This Hypothesis work at at all”. is currently up on the exoplanet.eu website in the bibliography section. If he is right, and I strongly suspect he is; this almost certainly NEGATES the Seligman et al “pendulum” comet proposal which almost everyone in the astronomical community immediately COMPLETELY bought into just to get rid of the issue altogether! This leaves only three solutions on the table: ONE, his “dust only” comet fragment. TWO, Bialy and Loeb’s “thin film or lightsail”(more on this later). And THREE: Katz’s REJECTION of Miceli’s 8.6 sigma non-gravitation data(which was ONLY up on ArXiv a couple of months ago and has yet to be published, which makes me VERY SUSPICIOUS of this one). Now, getting back to the “thin film or lightsail” solution. A very intreguing paper appeared on Vox Charta today entitled “Unusual Infrared Emission toward SGR B@: Possible Planar C$_{24} $”. by X. H. Chen, F. Y. Xiang, X. J. Yang, Aigen Li. The KEY word is “planar”, i.e. as in a two molecule thick graphene SHEET produced NATURALLY! The authors did NOT propose this to be an `Oumuamua-sized sheet, but, could such a massivly scaled-up sheet form naturally in interstellar space(i.e. NO NEED for a ejection mechanism from a planetary system), and over the eons, become coated with an 0.3mm coating of red organic goo, and then survive to enter our solar system. This is a real stretch, I believe, but not entirely implausible.

Dear Greg,
I very much respect your opinion and have learned things I did not know or have even thought about until you posted them on Paul’s blog. It’s just my opinion that if we want to be taken seriously, then we should not stray into our science fiction roots until we have unequivocal empirical evidence lest we become a 21st century Don Quixote.

How much of an increase in velocity in age can be accounted for simply by a combination of conservation of momentum and mass loss activity? It’s reasonable to propose that both the steller wind and CME have time averages that are centrally symmetric and thus yield zero net momentum change. Stellar mass goes down; velocity increases.

I looked in to mass loss. I don’t think that this is adequate. But it is always possible that I overlooked something. Also, be aware that the apparent acceleration of stars with age is a single data point. it must be confirmed either by future Gaia data releases or by other instruments.

I never thought that I would be doing this, but I am about to invoke big ideas from Madeline Engel’s “A Wrinkle in Time” TWICE! First, consider the tesseract(the kind she invisioned, NOT the infinity stone)as a way to move the stars faster, although these tesseracts would have to be rather small and exist entirely in the stars themselves. Secondly, I simply refuse to accept that stars as a WHOLE can possess conciousness, as she did. However, entire alien civilizations living entirely WITHIN stars at the low end of the stellar temperature scale lie entirely within the limits of my belief system! Finally, the now disproven “low mass companion” to Boyajian’s Star may have origionally BEEN a true companion and is now just moving on. If it could be PROVEN that its current path IS in the direction of galactic rotation, that would be really interesting indeed!

As I recall, the star nearest Boyajian’s Star is a few thousand Astronomical Units distant. It is not impossible that an advanced civilization at Boyajian’s Star could, as suggested by the Benfords, use a reflective megastructure to beam photons towards starships migrating to the stellar neighbor. Until and if a century-duration source of ~1-micron dust particles at Boyajian’s Star is found, such a possibility is still on the table. I have seen no information regarding the galactic orbit of the neighbor star. I must check out Madeline Engel’s book. Thanks for the lead.

Actors are focused on making a living at their chosen profession. We can expect little else from them. The two problems here are the hype and overattention they get from the media, which they often create themselves as part of that making a living thing I mentioned, and the confusion which arises when we mistake their on-screen personas for their real selves.

Is there some sort of hypothesis as to WHY a low mass star would “want” or “choose” to rotate about the galactic center faster than expected? Are there any conceivable advantages?

How certain are we that these low mass star’s behavior is a galaxy wide and not just a local phenomenon?

And probably not possible to observe …but do low mass stars exhibit this behavior in other galaxies? Also probably not yet possible….. But do brown dwarfs exhibit this behavior? Seems it would be way more pronounced in extremely low mass stars and brown dwarfs, the less the mass the faster rotation….

My money would be on higher massed stars including black holes throwing them out as they move in towards the centre. There is a natural tendency for massive objects to move to the centre by dynamic interaction and move low massed ones out.

Regarding velocity with mass, the acceleration and final velocity will depend on the rate of mass loss and the rocket equation. However, as Greg has mentioned, calculations show that CMEs and the solar wind cannot account for the velocity observed, by orders of magnitude. The numbers look better if the mass is ejected at light speed, but even then…

As they say, extraordinary claims require extraordinary proof. We have an observable phenomenon here, we think. That is the Parenago effect. What we now need is a testable hypotheses surely? And a lot more data. For example the stellar velocity versus age graph. It has only 7 points and none for stars between 4 and 6 billion years in age.

Fascinating developments on this area. For me this shows again how little we know about the universe.

Either it’s evidence of some unknown physical phenomenon working over lower mass stars as they age, which is interesting on itself, or of something else entirely, including volition (the Kardashev L3 kind or primitive consciousness in the stars themselves).

But certainly, the most interesting part is that the stellar chemistry discontinuity is still there, and now some stellar age factor appears, probably indicating gradual acceleration.

Personally, I’d prefer the K3 hypothesis being true, but the uniformity of the behavior across stellar populations makes this very unlikely (why are they showing such a similar swarm behavior?), unless all the rest of galaxy was in a party we weren’t invited at all.

But who knows? someone has said that any sufficiently advanced technology maybe indistinguishable from magic, and other going farther in the scale, also tell that it can become indistinguishable from nature!

I should have said previously that the whole set of observations your discussions above are fascinating. Thank you for having the courage to voice your opinions Alex and Greg. These ideas will intrigue people for a long time to come. I still prefer Occam’s razor when considering possibilities. And as for Tabby’s star the dust theory does seem to be the strongest and the most likely explanation. The specifics need to be worked out and there may be other factors involving the star itself.

We know from the historic rate of star formation that the galaxy has been capable of producing planets with environments like ours for almost ten billion years. This would strongly suggest that if we are not alone within the Milky Way galaxy that many civilizations could have had an enormous head start. My computer simulations suggest the first intelligence’s to emerge could have had whole geologic epochs to explore every nook and cranny of the galaxy long before our emergence many times over at only one percent of the speed of light.

The pessimist might say this question is moot. That maybe all civilizations have finite life spans measured in thousands and not millions or billions of years because of resource depletion or self-annihilation…or that maybe they simply turn solipsistic. These scenarios, however, would imply a uniformity of motive among all civilizations across both light years of distance and mega years of time. It would take only a small subset of societies to abrogate this uniformity for it to break down, so it is not very likely to exist.

Therefore, if we are not alone in the galaxy, and our uniqueness is a distinct possibility, then intelligent life has evolved on numerous occasions in the distant past, has had tens of millions of years or more to migrate across the galaxy, and has intentionally left us alone each time. The staggering implications of these ideas fill my dreams. I am sorry, but sentient stars is a bridge too far.
Temporal Dispersion of the Emergence of Intelligence: an Inter-arrival Time Analysis.

But just suppose intelligent, technological life is very rare. Then there may well not be the numbers to allow even one civ to break out of its system and colonize the galaxy. If we are the most advanced species in the galaxy today and we fail to colonize the stars, then any other intelligence will wonder why the galaxy appears empty.

The “conservative” assumptions by Drake and his peers on the number of civilizations in our galaxy may be far too optimistic. We just do not know.

Of course, it may be that we couldn’t recognize the presence of an advanced star faring civilization if it stepped on our figurative doorstep. Just like those ants, we cannot see other anthills or ants and assume the ir patch of ground is ant-free, failing to understand what those vertical gray rocks are…

Alex, we will absolutely colonize the stars (most probably our children of the mind). It is a foregone conclusion. Nothing in the universe, not even a giant black hole in an elliptical galaxy, is more powerful than the consciousness we have attained and that of possible others who may have come long before us and are still there (remember, we may be unique). The will of a conscious being to live another day is the most powerful force in the universe. Anything else is over socialized/intellectualized nonsense we learn when we have the ability to converse with like minded souls in our science fiction loving bubble.

(…) we will absolutely colonize the stars (most probably our children of the mind). It is a foregone conclusion.

I have to disagree with this version of “manifest destiny”. It is not certain or predetermined. It will require a technology that is cost effective within the size of the economy this system has at the time. It will need to be a very large economy if that technology is sending meat bodies in large starships. A smaller one if the agent is microscopic and the starship tiny, e.g. Breakthrough Starship sized. There is no guarantee that human intelligence will ensure our species survival to reach the size of economy needed and teh technology required.

The will of a conscious being to live another day is the most powerful force in the universe.

Vertebrates have a “fight or flight” response. Religions with a promise of afterlife may be a cultural invention that reinforces the fight response over flight, providing advantages for our species’ tribes to win the Darwinian selection. It isn’t that “living another day” is so powerful, but rather the fear of non-existence is so powerful. Afterlives allow the living to fight more cohesively and not grieve so intensely over those that died in the fighting.
Gene survival through kin protection is a mechanism for survival through proxies for non-afterlife-believing animals and humans.

Individual or group survival is not predicated on colonizing the galaxy. If it is possible, then it will require a reason to so that cannot be satisfactorily met any other way. It isn’t some “drive”.

Alex, You nailed it! It is more precisely stated by you. “the fear of non-existence” now has become my go to statement on this subject. I have long believed that no sentient “meat” will ever pass between stars, but I do believe the algorithm running through your head and mine will surely reach its manifest destiny because you and I are right now willing it into fruition via this very conversation.

This is humanity’s problem: One data point to go on, namely us. Very short life spans both individually and as a species. Astronomy is a relatively new science – just a few centuries ago we were still uncertain if Earth went around the Sun or vice versa, let alone anything more complex. Heck, less than ONE century ago we weren’t certain if there was one big galaxy (ours) or lots of others.

So when it comes to thinking about ETI or just alien life in general, we tend to think it will act and look like us. The “corrupting” influences of Star Trek and Star Wars are still with us. How many truly alien beings are in those franchises?

While the jury is still well out in regards to stars and whole galaxies being sentient beings, it would not surprise me in the least if it turns out we were looking for the wrong types in the wrong places all along, while ironically being surrounded by life in ways only a few have even grasped.

With all due respect, Drake et al are from the old school of thinking when it comes to SETI. They kept the idea that aliens would only live on Earth-type planets circling Sol-type stars and beaming just radio signals into the void for decades, largely because that is all they had to work with at the time.

Glad to see SETI is finally expanding, especially with the idea of looking for technosignatures. They too may turn out to be just another dead end or some equivalent for us, but at least it is a real move in the right direction, mainly that alien minds are going to be ALIEN, not some variation of us like in Star Trek.

Wow, that’s extremely interesting Thomas. Either they intentionally left us alone or we weren’t here yet (ie. they visited many thousands of years ago or more) or they visited more recently and we just don’t believe the cultural stories we have retained. Strangely enough we (some humans anyway) believe in a virgin birth but don’t believe it is possible we might have been visited by intelligent aliens long ago. Go figure.

The recent Hubble Constant discontinuities seem to show dark energy show up to give a boost at just the right times. If we could figure it out we would know perhaps how to move spacetime. Well not holding my breath.
There was another old saying like Oocham. Everytime we discover one answer we get 10 new questions. Sure looks like that is the case.

It would be amusing if Dark Energy was the result of a lot of anti-gravity propulsion. Perhaps it is like the polluting exhaust from our gasoline engines, and granular plotting of its distribution shows us where the drives have been or are operating. ;)

…the Universal Gravitational Constant G having a possible variable value is unlikely as it can be reduced to the light speed constant c, I will try find the paper again. In order for c to change so must the electrical fine constant, which appears not to have varied by much or zero to a very high accuracy.

I usually try to respond to each commenter on one of my pieces in this blog. I must apologize–we have had company and my computer time this week has been limited. But here are a few observations:

(1) Having met rupert sheldrake, I am convinced that he is an authentic, although unconventional scientist. He studied biology at elite UK universities and then worked at a biological research center in Hydrabod, India. His exposure to a Hindu sect that claims to be able to contact the Sun may explain his interest in this work. Although he may not have published his Conscious Star thoughts as yet, you can access some of his lectures on YouTube. Please search for “Sheldrake, Conscious Stars”.

(2) When stellar kinetics experts have completed their analysis of Gaia DR2, i suspect that more Parenago papers will be published. The DR1 paper cited in this blog piece indicates that the Discontinuity is non-local, which falsifies a number of theories. But is it galactic or universal?

(3) As I anticipated the Gaia DR1 Parenago paper, I wondered what types of explanations would arise for a non=local Parenago Discontinuity. Although I was quite sure that some hypothesis would arise to compete with Volitional Stars, the concept of an engineered K3 galaxy knocked my socks off. It is interesting that we seem to have three competing explanations for a non-local or universal Parenago Discontinuity: more strange properties for undetectable dark matter, a conscious universe, or an engineered universe. All are fascinating and require additional verification or validation.

Regarding your comments in Item 3 above, it would not surprise me at all if we were in Kardashev Type 3 galaxy and had no real clue, ala the ant colony at a construction site analogy. Most people never bother to think about such things, while most professionals are often too leery or too calcified in their thinking to consider such things at the moment, and certainly not in public.

Could the microbes that surround us actually be encoded with interstellar messages from some far-flung race of space aliens? It’s a question that has been posed for decades by some members of the SETI (Search for Extraterrestrial Intelligence) community. But most recently it was tackled by longtime space advocate Robert Zubrin, at this month’s ‘Breakthrough Discuss 2019’ conference at the University of California at Berkeley.

Given that we are now capable of sequencing the entire human genome, it’s not so far-fetched to think that we might be well-served to look for patterns, even messages in strands of bacterial DNA. Such microbes might make the perfect conduit for an interstellar Encyclopedia Galactica.

The idea is that once they are launched intentionally or even unintentionally, bacteria can travel interstellar distances and potentially seed the universe with messages from whoever encrypted them.

An individual bacterium — which typically ranges in size between one and ten-millionths of a meter — can easily replicate itself. But how could such tiny microbes naturally overcome their star’s gravity in order to make an interstellar journey?

Most likely through light pressure from their star’s outflow of photons, Zubrin, an astronautical engineer who is founder and president of The Mars Society, told me. This method of bacteria transmission would work best for brighter stars such as F-, G-, and K- spectral type stars. However, Zubrin notes that Red dwarf M-stars, the cosmos’ most ubiquitous, might have a difficult time pushing their bacteria outside their solar systems.

Yet if a bacterial colony was strongly magnetized, as Zubrin noted in a 2017 article posted on the popular space blog, Centauri Dreams, it might be able to act as a miniature magnetic sail. If so, it would, in theory, catch a 500 kilometer-per-second solar wind. That’s more than enough to propel it out of the solar system.

The problem I have with bacteria as a specific, rather than general message, is that they quickly mutate. Any message coded in their genes will quickly become garbled. They do convey the general message that “life exists” and furthermore, that message continues the process.

I do not see how any specific message could be encoded in the genome sequence as we would have no way to decode its meaning unless it was very simple. For example if the genome was a picture of prime1 x prime2 dimensions, and one of the 4 bases was an ON bit versus an OFF bit, making a 2D, monochrome image. That might be sufficiently noise tolerant for anyone to decode the image.

In such a way might bacteria consist of 2 different messages. Definitely shades of Lem’s “His Master’s Voice”.

These results were published on April 29, 2019 in Nature Astronomy (Qian-Fan Xing, Gang Zhao, Wako Aoki, Satoshi Honda, Hai-Ning Li, Miho N. Ishigaki & Tadafumi Matsuno, “Evidence for the accretion origin of halo stars with an extreme r-process enhancement”) as Advance Online Publication. This research is supported by the joint program of JSPS-Chinese Academy of Science since 2016, and KAKENHI (Nos. 16H02168 and 17K14249). The observation with the Subaru Telescope was conducted in the intensive program in 2016-2017.

We consider how an advanced civilization might build a radiator to send gravitational waves signals by using small black holes. Micro black holes on the scale of centimeters but with masses of asteroids to planets are manipulated with a super advanced instrumentality, possibly with very large electromagnetic fields.

The machine envisioned emits gravitational waves in the GHz frequency range. If the source to receiver distance is a characteristic length in the galaxy, up to 10000 light years, the masses involved are at least planetary in magnitude.

To provide the energy for this system we posit a very advanced civilization that has a Kerr black hole at its disposal and can extract energy by way of super-radiance. Background gravitational radiation sets a limit on the dimensionless amplitude that can be measured at interstellar distance using a LIGO like detector.

Comments: 19 pages

Subjects: Popular Physics (physics.pop-ph); General Relativity and Quantum Cosmology (gr-qc)

The great equalizer in all communication across vast ranges is the speed of light and gravwaves alike. This leads to motives, once societies achieve technologies. The grand goals of alien minds can be imagined [12]. Briefly, they can be…

• Kilroy Was Here—memorials

• High Church—records of a culture’s highest achievements. The essential message is this was the best we did; remember it. A society that is stable over thousands of years may invest resources in either of these paths. The human prospect has advanced enormously in only a few centuries; the lifespan in the advanced societies has risen by 50% in each of the last two centuries. Living longer, we contemplate longer legacies. Time capsules and ever-proliferating monuments testify to our urge to leave behind tributes or works in concrete ways. The urge to propagate culture quite probably will be a universal aspect of intelligent,technological, mortal species (Minsky, 1985).

• The Funeral Pyre: A civilization near the end of its life announces its existence.

• Ozymandias: Here the motivation is sheer pride; the Beacon announces the existence of a high civilization, even though it may be extinct, and the Beacon tended by robots.

• Help! Quite possibly societies that plan over time scales ~1000 years will foresee physical problems and wish to discover if others have surmounted them. An example is a civilization whose star is warming (as ours is), which may wish to move their planet outward with gravitational tugs. Many others are possible.

• Join Us: Religion may be a galactic commonplace; after all, it is here. Seeking converts is common, too, and electromagnetic preaching fits a frequent meme.

These motives may well persist into cultures vastly more powerful than ours, who prefer gravwave signals to the easier electromagnetic ones. They may choose gravwaves because they do not wish to be known to mere electromagnetic civilizations. LIGO has opened a window that perhaps few societies in our galaxy could manage, or wish to. It may show us more than astronomers expect.

It is also possible that we have overestimated the technical difficulties. Received power can be enhanced in transmissions if sources are made coherent. In gravitational radiation, this would mean resonant paralleling of trajectories in the smaller masses, as they orbit the central mass. This might be possible, but will greatly complicate matters, as the zoom-whirl orbits are already highly nonlinear; adding a coherence constraint makes their management more difficult.

One can also imagine an array of more than one m/M system. This would mean spacing the large mass elements in order for their emissions to align. Such an array then can direct emissions in a narrower spatial and perhaps frequency band, just as in electromagnetic systems. Some efficiency improvements seem possible this way. If so, the threshold of gravwave emitters may be low enough to make it a commonplace of truly long-lived societies.

“My rule is there is nothing so big nor so crazy that one out of a million technological societies may not feel itself driven to do, provided it is physically possible.”

Studies on extraterrestrial civilisations in Russia date back to the end of the 19th century. The modern period of SETI studies began in the USSR in the early 1960s. The first edition of the I.S. Shklovsky’s book {\it Universe, Life, Intelligence} published in 1962 was a founding stone of SETI research in the USSR. A number of observational projects in radio and optical domains were conducted in the 1960s – 1990s. Theoretical studies focused on defining optimal spectral domains for search of artificial electromagnetic signals, selection of celestial targets in search for ETI, optimal methods for encoding and decoding of interstellar messages, estimating the magnitude of astro-engineering activity of ETI, and developing philosophical background of the SETI problem.

Later, in the 1990s and in the first two decades of the 21st century, in spite of acute underfunding and other problems facing the scientific community in Russia and other countries of the former Soviet Union, SETI-oriented research continued.

In particular, SETI collaborations conducted a number of surveys of Sun-like stars in the Milky Way, searched for Dyson spheres and artificial optical signals. Several space broadcasting programs were conducted too, including a radio transmission toward selected stars. Serious rethinking was given to incentives for passive and active participation of space civilisations in SETI and CETI.

This paper gives an overview of past SETI activities. It also gives a comprehensive list of publications by authors from Russia, the Soviet Union and the post-Soviet space, as well as some SETI publications by other authors.

The rich heritage of SETI research presented in the paper might offer a potentially useful background and starting point for developing strategy and specific research programs of the near future.

Comments: 51 pages, 4 figures, 179 references

Subjects: Instrumentation and Methods for Astrophysics (astro-ph.IM); Popular Physics (physics.pop-ph)

In a recent paper in this journal, Lingam and Loeb (2018) develop an excellent heuristic for searches for biosignatures vs. technosignatures. We consider two ways in which their approach could be extended and sharpened, with focus on durability of technosignatures. We also note an important consequence of the adopted heuristic which offers strong support to the ideas of the Dysonian SETI.

Throughout this comment, we have fully accepted the tacit premise of LL18 (universally accepted in the current astrobiology/SETI discourse) that biosignatures are clearly and unambiguously distinguishable from technosignatures.

One interesting speculative possibility which perhaps deserves more attention – and is anyway necessary for the logical closure of discussions of detectability – is that the distinction between biological and technological might eventually be erased. The two could be fused in a sort of “biological artefacts”, such as growing/self-repairing megaengineering structures or the Black Cloud of Lem’s novel The Invincible (Lem [1964] 1973). This is related to the possibilities offered by postbiological evolution – and what comes beyond it (Ćirković 2018).

While it is impossible to give a more precise quantitative form to this merging hypothesis yet, we should keep it in mind in any future detailed study. (We thank an anonymous referee for bringing our attention to this radical possibility.)

All in all, the ingenious heuristics of LL18 actually gives strong support to the search for technosignatures, and in particular those persistent technosignatures with long durabilities. As our SETI observations increase in sensitivity and scope, there are reasons for optimism regarding both quantitative and qualitative insights into the parameter space of intelligent life in its most general cosmic context.

In the dramatic false-color radio images above, captured by the Canadian Galactic Plane Survey (background) and the Very Large Array (zoomed-in inset), a pulsar — a rapidly spinning, magnetized neutron star — is seen plunging out of a supernova remnant and taking off into interstellar space. The green cross marks the center of the supernova remnant CTB 1, and the green circle marks the location of the pulsar PSR J0002+6216.

The tail of radio-emitting gas extending behind the pulsar toward the nebula is a dead giveaway to this object’s origin: the pulsar was likely born from the very same supernova explosion that produced the remnant.

Supernova explosions don’t have perfect symmetry, and the pulsar likely received a natal kick that sent it tearing away from its birthplace at tremendous speeds, causing it to eventually overtake the expanding shell of gas and dust.

In a recent study led by Frank Schinzel (National Radio Astronomy Observatory), a team of scientists presents and discusses the evidence that this runaway pulsar came from CTB 1. To read more, check out the article below.

In Centauri Dreams, Paul Gilster looks at peer-reviewed research on deep space exploration, with an eye toward interstellar possibilities. For the last twelve years, this site coordinated its efforts with the Tau Zero Foundation. It now serves as an independent forum for deep space news and ideas. In the logo above, the leftmost star is Alpha Centauri, a triple system closer than any other star, and a primary target for early interstellar probes. To its right is Beta Centauri (not a part of the Alpha Centauri system), with Beta, Gamma, Delta and Epsilon Crucis, stars in the Southern Cross, visible at the far right (image: Marco Lorenzi).

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